1. Technical Field
The present invention relates to an image display method, an image display device, and a projector.
2. Related Art
An image display device such as a television displays an image in each frame. For example, at a frame frequency of 60 Hz, an image of an object is displayed at a slightly different position in each frame to produce a moving image of the movement of the object.
FIG. 14 Part A through FIG. 17 Part A show display images in each frame of a moving image of a moving object, time being represented by the vertical axis. FIG. 14 Part B through FIG. 17 Part B are views of a moving object when tracked by the line of sight.
FIG. 14 shows an image display made by a momentary-type image display device such as a CRT (Cathode Ray Tube). As shown in FIG. 14 Part A, a momentary-type image display device momentarily displays an image of the moving object in each frame (IF). Accordingly, as shown in FIG. 14 Part B, the blur 70 of the outline of the moving image decreases when tracked by the line of sight.
FIG. 15 shows an image display made by a continuous-type image display device such as a LCD (Liquid Crystal Display). As shown in FIG. 15 Part A, the continuous-type image display device continuously displays an image of the moving object during one frame. In this case, the outline position 72 of the moving object changes cyclically with a wide amplitude and, as shown in FIG. 15 Part B, the blur 70 of the outline increases when tracked by the line of sight.
In the natural world, the outline of a moving object decreases when tracked by the line of sight and appears unclear when not tracked. Visual characteristics such as those of FIG. 14 are therefore also desirable in a continuous-type image display device such as a liquid crystal display device.
As a solution, for example, JP-A-2002-351382 discloses (1) a method of intermittently displaying an image in the same manner as a momentary-type image display device in a continuous-type image display device, and (2) a method of displaying an image by doubling the frame frequency of an input image signal and inserting a generated image signal between continuous frames of input image signals.
FIG. 16 shows an intermittent image display in a continuous-type image display device. As shown in FIG. 16 Part A, a black display period is provided in each frame. As shown in FIG. 16 Part B, this reduces the blur 70 of the outline of the moving object.
FIG. 17 shows an image by inserting a generated image signal between continuous frames of input image signals. As shown in FIG. 17 Part A, an intermediate generated image signal is inserted between two continuous frames of input image signals. Consequently, there is less difference of the outline position 72 of the moving object between frames, and, as shown in FIG. 17 Part B, the blur 70 of the outline of the moving object decreases.
However, the method (1) of intermittent image display in a continuous-type image display device includes a black display period, which leads to a problem in that the image is darker than in heretofore continuous-type image display devices. The flickering image may also be painful to eyes of an observer.
The method (2) of image display by doubling the frame frequency of the input image signal and inserting a generated image signal has a problem that, since a new image signal is generated by calculating the motion vector and the like after precisely capturing the movement of the moving object, the load of the arithmetic processor greatly increases. Moreover, since an error in the generated image will cause flickering, the new image signal must be generated with high precision.
As described above, a continuous-type image display device should ideally have visual characteristics similar to those of the natural world. While the methods of (1) and (2) reduce the blur of the outline of a moving object when tracked by the line of sight, they have difficulties in solving the above problems. In each method, the outline of the moving object is visible even when not tracked by the line of sight, leading to a problem that the display is unnatural.